With development of science and technology, more high-performance servers are applied to scientific research and enterprise business activities. A large-scale x86 cache coherent non-uniform memory access (Cache Coherent Non-Uniform Memory Access, CC-NUMA) architecture system is widely applied by virtue of its features such as high performance, high scalability, and an easily programmable environment.
In the large-scale CC-NUMA system, generally a plurality of separate server mainboards (node boards) are interconnected by a cache coherent interconnect network to form a large server that runs only one operating system. Generally, in the large-scale x86 CC-NUMA multi-CPU system, based on each 2-CPU or 4-CPU node board, a BIOS of each node board is usually started first; in a BIOS startup process of each node board, unified memory addressing is performed, and a global address space of the system is configured; subsequently, in a phase of the BIOS process, each node is incorporated into one BIOS process for management and startup; and a complete multi-CPU system is formed by using this BIOS and provided to an operating system.
In an earlier phase of BIOS startup, because a CPU runs in a 32-bit (bit) mode, only a 4-kilomegabyte (KilomegaByte, GB) address space can be addressed. In addition, because each node board needs to access a memory mapped configuration (Memory Mapped config, MMCFG) space during memory initialization, space addressing in a position below 4 GB is required for the MMCFG space.
However, as a quantity of central processing units (Central Processing Unit, CPU) included in the large-scale CC-NUMA system increases, a size of an MMCFG space occupied by each CPU is fixed, and the MMCFG space in the position below 4 GB also increases. Because an address capacity in the position below 4 GB is fixed and limited, on one hand, a memory mapped input/output (Memory Mapped Input/Output, MMIO) space is caused to decrease, and the relatively small MMIO space limits a quantity and functions of Peripheral Component Interface Express (PCIE) devices. Consequently, the large-scale CC-NUMA system product has low compatibility with the PCIE devices. On the other hand, an available memory address space below 4 GB is also caused to decrease, and excessively low memory may cause a compatibility problem that the operating system cannot be started.